An example of a gas sensor for detecting a particular gas component contained in gas to be measured is a gas sensor having a longitudinally extending plate-shaped cell for generating a sensor signal in accordance with the particular gas component; an insulating substrate which is formed of a plate-shaped insulating material laminated on the cell and which has a plurality of through holes in a rear end region thereof, which through holes extend through the insulating substrate in its thickness direction and have conductors disposed therein; and a plurality of electrode pads disposed on an outer surface of the insulating substrate and electrically connected to the cell through the plurality of through holes (more specifically, the conductors disposed therein) for outputting the sensor signal to the outside of the sensor.
An example of such a conventional cell is an embedded-type cell which includes a frame member formed of a longitudinally extending plate-shaped insulating material and having a hollow space in a forward end region thereof, a solid electrolyte body disposed within the hollow space, a pair of electrodes formed on outer surfaces of the solid electrolyte body; a pair of longitudinally extending leads connected to the electrodes (Japanese Patent No. 4093784).
Adoption of such an embedded-type cell reduces the amount of the solid electrolyte body used in the cell, thereby reducing manufacturing costs of the gas sensor.
Another gas sensor for detecting a particular gas component contained in gas to be measured includes, in addition to all the above-described elements of the conventional gas sensor, a plurality of connection terminals connected to the electrode pads, and a metallic shell for holding the gas sensor element in a state in which the connection terminals are connected to the electrode pads (Japanese Patent No. 4093784).